Recently, as next-generation nonvolatile semiconductor memories, resistance-change memories have been attracting attention, such as a resistive RAM (ReRAM) in which a variable-resistance element serves as a memory element, and a phase-change RAM (PCRAM) in which a phase-change element serves as a memory element.
These resistance-change memories relatively easily allow the miniaturization of elements, and enable a higher memory capacity by three-dimensional integration that uses a cross-point memory cell array. The resistance-change memories are also capable of the same high-speed operation as that of a DRAM.
The resistance-change memory having such characteristics, when put into practical use, can replace, for example, a flash memory as a file memory and a DRAM as a work memory. Accordingly, various configurations and operations of the resistance-change memories have been suggested.
For the practical use of the resistance-change memories, improvements in memory characteristics, such as higher-speed operation, higher reliability, and lower power consumption are demanded for the resistance-change memories.